Patent GB-152099-A (GB)
Abstract: 152,099. Automatic Telephone Manufacturing Co., and Flynn, G. W. July 4, 1919. Party-line systems and apparatus.-In selective signalling systems such as are used for calling telephone stations connected to a party line, the stations are selected by sending a number of independent series of impulses by dial switches as in automatic exchange systems, operated at a control station. The initial series prepares the indicator circuit at a group of stations and the station is finally selected from this group by the subsequent series of impulses which complete the indicator circuit at the desired station. Each out-station is provided with a step-by-step rotary switch, the contacts of which are connected to the local circuits in a manner peculiar to that station. Means are provided whereby all the stations, or a group of stations, may be called simultaneously. The ringing of the bell at the desired station is audible to the operator at the control station. Fig. 1 shows the circuits at the control station, and Fig. 2 those at the out-station. When the operator desires to call a station the key 1 is moved to the right, closing a circuit from battery through springs 6, 7, impulse transmitter 3 and impulse relay 5. The line AB is also connected to the leads of a battery 4 through springs 8, 9 and 18, 19, and inductance coils 10, 17. Shunt capacities 104, 105 are placed across the battery leads. The operator then dials the tens digit of the wanted number, say 53, each impulse opening the circuit of relay 5, operating the switch arms 12, 15 and causing an impulse of opposite polarity to the normal current to be sent to line. At all the outstations these impulses operate a polarized relay 20 and move its armature 28 from contact 29 to contact 32. A slow-release relay 27 holds contact 33 closed during a, sequence of impulses. The first closure of contact 32 makes a circuit through contact 33, stepping magnet 36 and slow-release. relay 35 in parallel, first contact 37 of the selector switch, arm 39, arc 40 and battery. The contact 41 is closed by the relay 35, and the arm 39 is stepped forward one step, thus opening the battery circuit. Subsequent impulses pass through relay 35 and driving magnet 36 in parallel, and through contact 41 to battery. The selector contacts are connected respectively to a row of terminals, and at all stations numbered with the same tens digit, say 5, a wire connexion is made from the fifth terminal to an adjacent bar 44. Thus when the arm 39 stops on the fifth step, a circuit is made at all stations numbered 50 - - 59 through battery, arc 40, arm 39, fifth terminal 42, bar 44, contact 45, and relay 47. During the steppings of the arm 39 current has passed from battery through off normal contact 48, resistance 49 and relay 47, but this is insufficient to operate the relay, although sufficient to maintain it operated. At the stations numbered 50 - - 59 the full energization of relay 47 closes contacts 50, 51. The operator then sends a series of impulses, say 3, corresponding to the units digit of the wanted number. The first of these impulses passes through relay 35 and stepping-magnet 36 in parallel, through contacts 50, 51, bar 44, terminal 42, selector arm 39 to battery. The remainder of the units impulses pass to battery through contact 41. The selector arm is thus moved forward an additional number of steps (three) equal to the units digit of the wanted number, 53. At this station a permanent connexion is made from the eighth terminal (5 + 3) to a bar 53, and a circuit is thus completed through battery, arc 40, eighth terminal, bar 53, contacts 54, 46, bell 55, and relay winding 56, the contact 46 being closed by the deenergization of the slow-release relay 35 at the conclusion of the impulses. When the called party removes his receiver 60, the instrument circuits are completed and a momentary impulse is sent from battery through springs 67, 66, 68 to the release magnet 69 by which the selector arm at the called station is returned to normal position, opening contact 48 and de-energizing relay 47, which opens the bell circuit at 54. The operator hears the bell owing to the inductive effect of the winding 56 on the polarized relay winding, the induction coil of her speaking set having' a winding 57 tapped off the inductance 10 in the impulse circuit. The winding 57 is short-circuited by an off normal switch 59 during the sending of the impulses. When the bell ceases ring- ing, the operator moves the key 1 to the left or speaking position, connecting her instruments to line and disconnecting the battery 4 and relay 5. The relays 20 at each out-station return to central position, the slow-release relay 27 allows a contact 80 to close, thus returning all the selector arms 39 to normal position. When the conversation is finished, the called party replaces his receiver, and the operator places her key 1 in normal position. An out-station may call up the operator by pressing the key 20<a>, which completes a circuit through a relay 90 at the control station and closes a battery circuit through a relay 92 which has a hold-on circuit, including a spring 81 controlled by the key 1. The relay, 92 lights a lamp 95 and energizes a night-alarm relay 96 controlling a bell 97. When the operator moves the key 1 to the speaking position, spring 81 is opened and the hold-on circuit is broken. To enable the operator to call all the out-stations, or a chosen group, simultaneously, the twentieth contact of the selector is connected to terminal 98, and the tenth contact, in addition to its connexion to the tenth terminal, has also a connexion to the end terminal 100. At all the stations of the chosen group a permanent connexion is made from terminals 98, 100 respectively to terminals 99, 102 adjacent to the bar 53. The operator dials 00, that is, two series of ten impulses. After the first ten impulses have been sent, a circuit is formed for the first impulse of the second series through battery, arc 40, arm 39, terminals 100, 102, contact 103, relay 35, and magnet 36 in parallel, contact 33, 32. The remaining impulses of the second series pass through contact 41. When the arm 39 reaches the twentieth contact, the bell circuits are completed through terminals 98, 100 and contact 46. Other numbers may be employed as group calls, by connecting at all stations of the group the tens bar 44 to the terminal corresponding to the tens digit, and the units bar 53 to the terminal corresponding to the sum of the tens and units digits.